This app provides a way to reserve battery power for calls and messages. It will let you set a threshold below which you don't want your device to run. This way, you can ensure that your phone will not run out of battery power even if you use it for a long period of time.

It has three modes: one is reserving battery for calls and messages and the other is extending the battery life. The last one is forwarding the messages to a contact instead when your phone is powered off.

It is very easy to use. You just need to install the app. When you use it for the first time, you need to create a login account.